Re: explanation for teleportation/entanglement?

[Kevin de Laplante <***>]

Tim,

> When you get a chance, I'd appreciate your comments on this paper, which
> primarily questions the validity of the Bell/CHSH/CH inequalities in
actual
> experiments. It strikes me as cogent, but I'm not informed enough to know
> for sure. It is largely non-technical:
> http://arxiv.org/abs/quant-ph/0210150
>
> Regards,
> Tim
>

We're in the same boat on this one!  I'd send it to a physicist who's
familiar with the literature.  My undergraduate major is physics, and I do
teach philosophy of physics, but it's not my primary research area (I do
philosophy of ecology, complexity, and environmental philosophy!).  Also,
though I do units on classical mechanics, special and general relativity,
and quantum mechanics, I teach primarily from source material that is
usually written by philosophers, since my audience is undergraduate science
and philosophy majors, and I can't assume either much physics or philosophy
background.  It's a course that employs a lot of argument analysis, but it
shies away from technical stuff when it can.  So I'm not well versed in the
technical aspects of the experimental tests of nonlocality.

A lot of philosophy of physics is written under the assumption that a given
theory is well confirmed within its domain of application, and goes on to
consider how to make metaphysical sense of this.  When it comes to
experimental tests of nonlocality (or theories generally), we tend to take
the word of the consensus of the physics community on whether a test is
good, significant, etc.  The Aspect experiments and their kind have this
status.  The paper you linked aims to challenge this status, but I'm not in
a position to assess the argument.

I've been thinking about your suggestion about testing nonlocality by making
a measurement of momentum on particle A, and then measure positions of
particle B to see if there's a greater spread.  The concern I have is
whether we should expect any effect of this kind.  This requires that
measurements of momentum of A will fail to commute with measurements of
position of B, but as far as I know that's not the case.  My understanding
is that position and momentum of the same particle will fail to commute, but
position and momentum of different particles can commute, even for entangled
states.  This is the case, I think, in the original EPR argument, and for
the Bohm version with spins.  I'm prepared to be wrong about this, though.

best,

Kevin